package com.fish.sqlSession;

import com.fish.pojo.Configuration;
import com.fish.pojo.MappedStatement;

import java.lang.reflect.*;
import java.util.List;

public class DefaultSqlSession implements Sqlsession {

    private Configuration configuration;

    public DefaultSqlSession(Configuration configuration) {
        this.configuration = configuration;
    }

    @Override
    public <E> List<E> selectList(String statementid,Object... params) throws Exception {
        MappedStatement mappedStatement = configuration.getMappedStatementMap().get(statementid);
        Executor executor = new SimpleExecutor();
        List<E> list = executor.query(configuration, mappedStatement,params);
        return list;
    }

    @Override
    public <T> T selectOne(String statementid,Object... params) throws Exception {
        List<Object> objects = selectList(statementid, params);
        if(objects.size()==1){
            return (T) objects.get(0);
        }else {
            throw new RuntimeException("查询结果为空或者返回结果过多");
        }
    }

    @Override
    public <T> T getMapper(Class<?> mapperClass) {
        Object newProxyInstance = Proxy.newProxyInstance(DefaultSqlSession.class.getClassLoader(), new Class[]{mapperClass}, new InvocationHandler() {
            @Override
            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
                // 底层都还是去执行JDBC代码 //根据不同情况，来调用selctList或者selectOne
                // 准备参数 1：statmentid :sql语句的唯一标识：namespace.id= 接口全限定名.方法名
                String methodName = method.getName();
                String className = method.getDeclaringClass().getName();

                String statementId = className+"."+methodName;
                MappedStatement mappedStatement = configuration.getMappedStatementMap().get(statementId);
                switch (mappedStatement.getSqlType()){
                    case "insert":
                        return insert(statementId, args);
                    case "update":
                        return update(statementId, args);
                    case "delete":
                        return delete(statementId, args);
                    default:
                        Type genericReturnType = method.getGenericReturnType();
                        // 判断是否进行了 泛型类型参数化
                        if(genericReturnType instanceof ParameterizedType){
                            List<Object> objects = selectList(statementId, args);
                            return objects;
                        }
                        return selectOne(statementId,args);
                }
            };
        });
        return (T) newProxyInstance;
    }

    @Override
    public boolean insert(String statementid, Object... params) throws Exception {
        MappedStatement mappedStatement = configuration.getMappedStatementMap().get(statementid);
        Executor executor = new SimpleExecutor();
        return executor.insert(configuration, mappedStatement,params);
    }

    @Override
    public int update(String statementid, Object... params) throws Exception {
        MappedStatement mappedStatement = configuration.getMappedStatementMap().get(statementid);
        Executor executor = new SimpleExecutor();
        return executor.update(configuration, mappedStatement,params);
    }

    @Override
    public boolean delete(String statementid, Object... params) throws Exception {
        MappedStatement mappedStatement = configuration.getMappedStatementMap().get(statementid);
        Executor executor = new SimpleExecutor();
        return executor.delete(configuration, mappedStatement,params);
    }
}
